codal_app/microbithal_audio: Add helper functions for sound exprs.

To check if a sound expression is playing, and to stop them playing.

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

src/codal_app/main.cpp

@@ -33,6 +33,7 @@ extern "C" void m_printf(...);
 extern "C" void microbit_hal_timer_callback(void);
 extern "C" void microbit_hal_gesture_callback(int);
 extern "C" void microbit_hal_level_detector_callback(int);
+extern "C" void microbit_hal_sound_synth_callback(int);
 extern "C" void microbit_radio_irq_handler(void);
 
 MicroBit uBit;
@@ -49,6 +50,10 @@ void level_detector_event_handler(Event evt) {
     microbit_hal_level_detector_callback(evt.value);
 }
 
+void sound_synth_event_handler(Event evt) {
+    microbit_hal_sound_synth_callback(evt.value);
+}
+
 int main() {
     uBit.init();
 
@@ -64,6 +69,7 @@ int main() {
     uBit.messageBus.listen(DEVICE_ID_SERIAL, CODAL_SERIAL_EVT_DELIM_MATCH, serial_interrupt_handler, MESSAGE_BUS_LISTENER_IMMEDIATE);
     uBit.messageBus.listen(DEVICE_ID_GESTURE, DEVICE_EVT_ANY, gesture_event_handler);
     uBit.messageBus.listen(DEVICE_ID_SYSTEM_LEVEL_DETECTOR, DEVICE_EVT_ANY, level_detector_event_handler);
+    uBit.messageBus.listen(DEVICE_ID_SOUND_EMOJI_SYNTHESIZER_0, DEVICE_EVT_ANY, sound_synth_event_handler);
 
     // 6ms follows the micro:bit v1 value
     system_timer_event_every(6, MICROPY_TIMER_EVENT, 1);

src/codal_app/microbithal.h

@@ -139,7 +139,9 @@ const uint8_t *microbit_hal_get_font_data(char c);
 void microbit_hal_audio_select_pin(int pin);
 void microbit_hal_audio_select_speaker(bool enable);
 void microbit_hal_audio_set_volume(int value);
+bool microbit_hal_audio_is_expression_active(void);
 void microbit_hal_audio_play_expression_by_name(const char *name);
+void microbit_hal_audio_stop_expression(void);
 
 void microbit_hal_audio_init(uint32_t sample_rate);
 void microbit_hal_audio_write_data(const uint8_t *buf, size_t num_samples);

src/codal_app/microbithal_audio.cpp

@@ -59,6 +59,8 @@ extern "C" {
 
 #include "microbithal.h"
 
+static uint8_t sound_synth_active_count = 0;
+
 void microbit_hal_audio_select_pin(int pin) {
     if (pin < 0) {
         uBit.audio.setPinEnabled(false);
@@ -81,10 +83,26 @@ void microbit_hal_audio_set_volume(int value) {
     }
 }
 
+void microbit_hal_sound_synth_callback(int event) {
+    if (event == DEVICE_SOUND_EMOJI_SYNTHESIZER_EVT_DONE) {
+        --sound_synth_active_count;
+    }
+}
+
+bool microbit_hal_audio_is_expression_active(void) {
+    return sound_synth_active_count > 0;
+}
+
 void microbit_hal_audio_play_expression_by_name(const char *name) {
+    ++sound_synth_active_count;
+    uBit.audio.soundExpressions.stop();
     uBit.audio.soundExpressions.playAsync(name);
 }
 
+void microbit_hal_audio_stop_expression(void) {
+    uBit.audio.soundExpressions.stop();
+}
+
 void microbit_hal_audio_init(uint32_t sample_rate) {
     if (!data_source.started) {
         MicroBitAudio::requestActivation();